On 2/9/11 2:08 PM, Tijd Dingen wrote: > > >> The autocorrelation processing is O(N^2) while the DFT can be done in >> O(N log N) when using FFT. As usual these can be implemented in reversed >> order such that first the FFT is done to the phase jitter and auto-correlation >> can be found using O(N) post-processing. > > If it can be done in N log N that would be nice. :) autocorrelation: FFT of input sequence, multiply each bin by itself, inverse FFT So N(2logN+1) operations

> LeCroy has a paper with a short explanation that I found useful: > > http://www.lecroy.com/files/WhitePapers/WP_TechBrief_Var_of_Time.pdf This look to me very similar to this: http://pstca.com/sampler/index.htm - Henry -- ehydra.dyndns.info

On 10/02/11 06:13, jimlux wrote: > On 2/9/11 2:08 PM, Tijd Dingen wrote: >> >> >>> The autocorrelation processing is O(N^2) while the DFT can be done in >>> O(N log N) when using FFT. As usual these can be implemented in reversed >>> order such that first the FFT is done to the phase jitter and >>> auto-correlation >>> can be found using O(N) post-processing. >> >> If it can be done in N log N that would be nice. :) > > autocorrelation: > FFT of input sequence, multiply each bin by itself, inverse FFT > > So N(2logN+1) operations Eh, no. In this case we wanted the frequency form, so no inverse FFT. You forgot to keep an eye on the big picture. Cheers, Magnus

----- Original Message ---- From: Magnus Danielson <magnus@rubidium.dyndns.org> To: time-nuts@febo.com Sent: Wed, February 9, 2011 10:08:40 PM Subject: Re: [time-nuts] Calculate spectral content from a series of zero crossing time stamps? > Wavecrest just fell of the Internet for some time and then eventually >re-appeared as GigaMax. All material quite > obvious just changed company name and logo. A few things was cleaned out. >Haven't checked since. > I would think they had financial problems and was reconstructed one way or >another. Looks like it. While searching for info I also noticed that (apparently) roundabout that time the CEO died at the age of 50-something. That's usually not optimal for stability either... > The DTS series got support from a new separate company, forgot the name but it >was a Wavecrest variant if I recall it correctly. Possibly this is the one you mean: http://wavecrestdts.com/ Anyways, for those interested in jitter, the papers in the technical resources section of gigamax are pretty good. Possibly old hat for people around here, but it was new and informative to me... http://gigamaxtech.com/technical/tech.html regards, Fred ____________________________________________________________________________________ Don't get soaked. Take a quick peak at the forecast with the Yahoo! Search weather shortcut. http://tools.search.yahoo.com/shortcuts/#loc_weather

On 11/02/11 20:26, Tijd Dingen wrote: >> Wavecrest just fell of the Internet for some time and then eventually >> re-appeared as GigaMax. All material quite >> obvious just changed company name and logo. A few things was cleaned out. >> Haven't checked since. > >> I would think they had financial problems and was reconstructed one way or >> another. > > Looks like it. While searching for info I also noticed that (apparently) > roundabout that time the CEO died at the age of > 50-something. That's usually not optimal for stability either... Ohoh, that would be sub-optimal in many ways. >> The DTS series got support from a new separate company, forgot the name but it >> was a Wavecrest variant if I recall it correctly. > > Possibly this is the one you mean: http://wavecrestdts.com/ Yes, that's it. Cheers, Magnus